There is a white china bowl in the fridge, its contents hidden under a plate. With luck it will be buried treasure: the remains of a casserole; steamed potatoes and greens ready for bubble and squeak; a squirrelled-away apple crumble. It is a sad day when the contents turn out to be some of yesterday’s pasta.

With luck, my dear old bowl will be full of soup whose character will have mellowed for having spent a night in the fridge. Such recipes are the backbone of my eating in January and February. The best of them begin with an onion, a rib of celery and a few bay leaves and will be started on a low heat, so the onions soften without much colour. I try to catch the onions just as they turn from white to gold, when you can crush them, effortlessly, against the side of the pot with the back of a spoon. You can add cooked haricots at this point, or chickpeas or butter beans; borlotti and black-eyed beans, too, the sort whose water turns dark pink-brown as they simmer. Before you know it, you have dinner.

So far so sustaining, but I want my fresh, vital winter greens, too. I like to finish any soup with something leafy. Frills of kale, tiny frost-crisped sprouts or shredded winter cabbage tossed in at the end will all do. The greens will lighten a long-cooked soup like a bright torch shining down a dark well. It is worth remembering those winter greens will also make a splendid cream soup. Shred the leaves then stir into softened onions and simmer with milk and crumbled cheese for a cold weather soup that manages to be both refined and rough edged at the same time.

Black eyed bean, rosemary and kale soup

A main-course soup, made reasurringly thick by blending a good third of it and returning it to the rest of the ingredients.

To finish:kale or brussels sprout tops 150gparsley leaves a good handfulolive oil to finish

Soak the beans overnight in a bowl of cold water. The next day, drain the beans, put them in a deep saucepan, cover with water and bring to the boil. Lower the heat, skim off any froth then add the bay leaves and leave at a gently rolling boil for an hour or until the beans are almost tender. Check the water level regularly. Remove from the heat, but leave the beans in the water.

Peel and roughly chop the onion and the carrot. Pull the needles from the rosemary sprigs and chop finely. Remove the leaves from the celery and reserve, then chop the celery into small pieces. Peel and finely chop the garlic.

Warm the olive oil in a heavy based saucepan. When it’s hot, add the onion, carrot, rosemary, celery and garlic and cook over a low heat for 15 minutes, until the vegetables are starting to soften.

Season with salt and pepper and continue cooking until everything is thick, rich and fragrant

Scrub the potato and cut into small dice. Roughly chop the tomato and stir it, together with the potato, into the softening vegetables and herbs. Cover the pan with a lid and continue cooking, stirring regularly, for 15-20 minutes until the potato has softened. Add the beans and 1 litre of their cooking liquid.

Season generously with salt and pepper and continue cooking for 30 minutes until everything is thick, rich and fragrant. Ladle one third of the mixture into a blender, process till smooth then stir back into the soup.

Pick over the kale or sprout tops, discarding anything that isn’t sparklingly fresh. Tear into pieces then dunk under the surface of the soup and leave to soften for 2 or 3 minutes.

Roughly chop the parsley and celery leaves. Ladle the soup into bowls, scatter with the chopped celery and parsley leaves and finish with a trickle of olive oil.

A soup of sprout tops and stilton

Say cheese: a soup of sprout tops and stilton. Photograph: Jonathan Lovekin for the Observer

The subtle eau de Nil colour darkens if you try to keep the soup for tomorrow. It’s best served as soon as it is made.

Serves 4milk 600mlstilton 200gonions 2butter 30gsprout tops 350g

To finish:butter 30gthe reserved sproutsstilton 100g

Bring the milk to the boil then remove from the heat. Crumble the stilton into the milk, cover with a lid and leave to infuse. Peel and roughly chop the onions.

Melt the butter in a deep pan and add the chopped onion. Fry gently over a moderate heat for about 10 minutes until the onion is glossy and sweet smelling. Separate the leaves of the sprout tops, pick off the whole sprouts, set aside and finely chop the stems. Add the stems and combine with the onion. Finely shred the sprout tops, stir into the onion and cook for 4 to 5 minutes, stirring almost constantly until the leaves are bright green and wilted. Add the infused milk and cheese mixture and bring almost to the boil. Ladle into a blender and process to a thick but not totally smooth soup. Check the seasoning – you are likely to need black pepper but not salt.

To finish, cut the reserved sprouts in half and fry lightly in the butter. Toss them with the stilton and add to each bowl as you serve.